云数据库 GaussDB-案例：调整基于代价的查询重写GUC参数costbased_rewrite_rule:案例环境准备

时间：2025-01-26 10:43:58

云数据库 GaussDB

案例环境准备

为了便于规则的使用场景演示，需准备建表语句如下：

SET client_min_messages = warning;SET CLIENT_ENCODING = 'UTF8';--清理环境。DROP SCHEMA IF EXISTS costbased_rule_test cascade;CREATE SCHEMA costbased_rule_test;SET current_schema = costbased_rule_test;SET enable_codegen = off;DROP TABLE IF EXISTS costbased_rule_test.ct1;DROP TABLE IF EXISTS costbased_rule_test.ct2;DROP TABLE IF EXISTS costbased_rule_test.ct3;DROP TABLE IF EXISTS costbased_rule_test.ct4;--创建测试表。CREATE TABLE ct1 (a INT, b INT, c INT, d INT);CREATE TABLE ct2 (a INT, b INT, c INT, d INT);CREATE TABLE ct3 (a INT, b INT, c INT, d INT);CREATE TABLE ct4 (a INT, b INT, c INT, d INT);CREATE INDEX idx_ct1_b ON ct1(b);CREATE INDEX idx_ct2_c ON ct2(c);CREATE INDEX idx_ct3_c ON ct3(c);--插入数据。INSERT INTO ct1 (a, b, c) VALUES (generate_series(1, 100), generate_series(200, 300), left(random()::int, 100));INSERT INTO ct2 VALUES(1,2,3,4),(3,4,5,6);INSERT INTO ct3 (a, b, c, d) VALUES (generate_series(1, 10), generate_series(20, 30), left(random()::int, 10), left(random()::int, 10));--更新统计信息。ANALYZE ct1;ANALYZE ct2;ANALYZE ct3;

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